Adbul Ubad, 26, who works at Empire News near the scene of the blaze on Wake Road in Nether Edge, said he served sweets to the boys the morning before the fire broke out.

“This has affected the whole community - everybody is upset, everyone is wondering why it happened,” he said. “The young boys bought sweets here the morning before. I can’t believe I won’t see them again.”

Investigators yesterday spent a second day at the house, carrying out a search of the charred building.

South Yorkshire Fire and Rescue Service area manager Phil Shillito said: “Specialist investigators are working hard to establish what caused this fire. Our thoughts remain with the family at what must be an extremely distressing time.”

A brigade spokesman added: “Investigations by specialist fire and police investigators have continued but so far nothing has been found which suggests the fire was started deliberately. Efforts continue to establish the exact cause.”

Flowers were left close to the house where tragedy struck in the early hours of Monday, while more were laid at the end of the street.

Coun Nikki Bond left flowers with a card which read: “Our thoughts are with those lost too soon and the family and friends left behind.”

Police Chf Supt David Hartley, District Commander of Sheffield, said ‘considerable efforts’ had been made by police and other emergency services to revive the victims at the scene.

“South Yorkshire Police remain at the scene, offering support to the local community who are understandably struggling to come to terms with this terrible tragedy.”